Following decades of renewable energy research, liquids derived from conversion of biomass (for example by rapid thermal processing, slow pyrolysis (for example a vacuum pyrolysis), catalytic pyrolysis, torrefaction, or hydrothermal processing, to name a few) are beginning to be used as petroleum substitutes in combustion and in refinery processes such as fluidized catalytic cracking.
One of the remaining challenges is to find cost-effective ways to remove contaminants from liquid biomass that may otherwise increase environmental emissions and/or complicate further processing. For example, rapid thermal processing of cellulosic biomass (for example wood, agricultural waste, etc.) may result in carryover of solids including char, ash, dissolved metals, and dissolved chlorine into the liquid biomass product. These contaminants can produce regulated emissions upon combustion, interfere with or poison catalysts used in refineries, and degrade process equipment (for example chlorine may result in stress cracking in metal equipment unless special alloys are used). These contaminants may also degrade the liquid biomass, thereby reducing shelf life and making it less useful. Char, for example, contributes to thermal instability, increases in viscosity, phase separation, and/or solids formation during storage.
Accordingly, methods, processes, systems, and apparatus are needed to produce liquid biomass having a relatively low contaminant concentration.